Ketonic Decarboxylation Catalysed by Weak Bases and Its Application to an Optically Pure Substrate

Abstract

Ketonic decarboxylation is a very old reaction that transforms two carboxylic acids into a ketone or a dicarboxylic acid into a cyclic ketone, in particular adipic acid into cyclopentanone. Herein it is reported that catalytic amounts of weak bases such as sodium carbonate can carry out this reaction selectively. This is in accordance with a mechanism involving decarboxylation and nucleophilic attack at a second carboxyl group. The reaction can be employed in asymmetric syntheses since the stereogenic centres in the β‐positions retain their stereochemistry. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

Synthesis and AChE inhibitory activity of new chiral tetrahydroacridine analogues from terpenic cyclanones

“…Oxidative cleavage of (R)-pulegone using RuCl 3 /NaIO 4 afforded the (R)-3-methyladipic acid 37 [38]. Next, 37 was subjected to ketonic decarboxylation and cyclization processes in the presence of catalytic Na 2 CO 3 under thermal conditions (Scheme 5) [39]. Mechanistic considerations, for the later reaction, involve an initial ketonic decarboxylation, followed by the attack of an unstable carbanion to the second carboxyl group, leading to the cyclopentanone 15.…”

“…The resultant solid was purified by silica gel flash chromatography using MeOH/CH 2 Cl 2 or alumina chromatography using hexane/ AcOEt as eluent to give pure compounds. (39). To a stirred solution of allylic alcohol 38 (1.34 g, 8.7 mmol) in CH 2 Cl 2 (60 mL) was added, slowly and at 0 C, a solution of mCPBA 65% (2.24 g, 13.0 mmol) in CH 2 Cl 2 (100 mL).…”

Ketonization of Carboxylic Acids by Decarboxylation: Mechanism and Scope

“…Thus, no difference is observed when performing the reaction using either sodium hydroxide or sodium carbonate as base. [45] Consequently, promoters for the ketonic decarboxylation of adipic acid include many kinds of bases, such as the strong potassium fluoride (Table 5, entry 9), hydroxides of alkali and alkali earth metals (entries 4-6 and 10), sodium phosphate (entry 11), and very weak carbonates (entry 12). Generally, cyclopentanone is obtained in 80-90% yield.…”

“…Chem. 2005, 979-988 www.eurjoc.org 1 adipic acid -60 [7] 2 adipic acid 290-300 -88-98 [8] 3 barium 430 -84 [8] adipate 4 adipic acid Ba(OH) 2 87 [5] (1.7 wt.-%) 5 adipic acid 285-295 Ba(OH) 2 80 [10] (5 wt.-%) 6 adipic acid 290-295 Ba(OH) 2 Ͼ95 [4] (4 mol-%) 7 adipic acid 270-280 U(NO 3 ) 4 85 [4] (4 mol-%) 8 adipic acid 270-280 FeSO 4 90 [4] (4 mol-%) 9 adipic acid 250-280 KF 81 [15] (5 mol-%) 10 adipic acid 350 NaOH 84 [45] (10 mol-%) [a] 11 adipic acid 250…”

“…For instance, when reacting dimethyl octanedioate in the presence of alumina, cycloheptanone is obtained in a regular yield of 29% (Table 8, entry 6) as opposed to 69% in the case of cyclopentanone (Table 6, entry 8). At the [45] (5 mol-%) 6 3 -tert-butyl 350 Na 2 CO 3 83 [45] (5 mol-%) 7 2,2-dimethyl 225 [a] Na 3 PO 4 77 [46] (23 mol-%) 8 2,2-dimethyl 225 [a] Na 2 B 4 O 7 80 [47] (19 mol-%) 9 2,2,5,5-tetramethyl 320-340 KF anhydrous 52 [15] (45 mol-%) 10 2,2,5,5-tetramethyl 320-330 BaO 72 [15] (15 mol-%)…”